Florida Sen. Marco Rubio told ABC’s “This Week” that he believed he was ready to be president and would take an all-or-nothing approach to running if he does decide to go ahead, while also sounding skeptical notes on climate change and Hillary Clinton‘s tenure as secretary of state — two likely hot issues in 2016.

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Asked by ABC’s Jonathan Karl if he thought he was ready, Mr. Rubio said quickly, “I do,” before adding some qualifiers.

“I think that’s true for multiple other people that would want to run. I mean, I’ll be 43 this month, but the other thing that perhaps people don’t realize: I’ve served now in public office for the better part of 14 years. And most importantly, I think a president has to have a clear vision of where the country needs to go and clear ideas about how to get it there. And I think we’re very blessed in our party to have a number of people that fit that criteria.”

Mr. Rubio also said he would not seek re-election as a senator if he did decide to run. “I believe that if you want to be president of the United States, you run for president,” he said. “You don’t run for president with some eject button in the cockpit that allows you to go on an exit ramp if it doesn’t work out.”

In the interview, Mr. Rubio also staked out blunt positions on two big potential issues in a 2016 run — climate change, and Hillary Clinton.

“I don’t agree with the notion that some are putting out there, including scientists, that somehow there are actions we can take today that would actually have an impact on what’s happening in our climate. Our climate is always changing,” he said.

He said that he didn’t give Mrs. Clinton “a passing grade” for her time as secretary of state. “I’m sure she’s going to go on bragging about her time in the State Department, she’s also going to have to be held accountable for its failures, whether it’s the failed reset with Russia or the failure in Benghazi that actually cost lives,” he said.

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